In this project we assess exposures to atmospheric PCBs among a cohort of children and their mothers in a contaminated area where dredging of PCB-laden sediments will occur during the study period. PCB concentrations are measured through repeated air sampling inside and outside of homes and local schools. Blood samples are collected annually and assayed for PCB congeners. These data are compared to a rural site to characterize high and low exposure residential cohorts. The urban site (East Chicago, IN) has a legacy of PCB contamination from intense past industrial activity whereas the rural site (Columbus Junction, IA) is without local sources of PCBs. The project will continue four original aims and pursue two new aims: Aim 1. Establish a residential cohort in East Chicago and a rural residential cohort in Columbus Junction; Aim 2. Measure emissions and exposures of atmospheric PCBs at homes and schools in these communities; Aim 3. Gather demographic, residential, occupational, activity and dietary information by questionnaire; Aim 4. Analyze data from these cohorts and develop an exposure model for the atmospheric PCB congeners. Aim 1 has been achieved but we will to expand the cohort to increase power and span the time before and during the dredging. Aim 2 and Aim 3 are ongoing. We continue to measure subjects' PCB exposures, collect blood samples and administer questionnaires. We have begun Aim 4 with analysis of survey data and congener-specific PCBs. Two new aims are planned for this renewal. Aim 5. Measure congener-specific hydroxy metabolites of PCBs in subjects' biobanked extracted and derivitized blood samples. Aim 6. Adapt a bioaccumulation model to predict the PCB body burden in subjects breathing air with measured PCBs levels and compare modelled data with measured data. Five hypotheses will be tested: H1: East Chicagoans have significantly higher exposures, and (H2) blood levels of atmospheric PCB congeners than rural lowans. H3: Adolescent's burdens of PCB congeners are significantly correlated with those of their mothers. H4: East Chicagoans will experience increased exposures with the dredging of Indiana Harbor and Ship Canals and filling of the Confined Disposal Facility. H5: Bioaccumulation models can predict the relative body burdens of PCBs using measured air data and dietary questionnaire data.